Flameproofing substrate

Abstract

Steel, wood and other structural elements and substrates are flameproofed by being coated with a composition comprising at least one metal salt of a phosphonocarboxylic or phosphonophosphonic acid of the formula ##STR1## in which R 1 =a carboxy group, a phosphono group, an alkyl, alkoxy or alkylamino radical optionally substituted one or more times by oxygen and/or nitrogen and containing at least one substituent from the group comprising the substitutents --COOH and --PO 3 H 2 , the alkyl group containing from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms, and the sum of the number of carboxyl and phosphono groups being from 1 to 8, preferably from 1 to 4; or a hydroxyalkyl or aminoalkyl radical containing from 1 to 12 and preferably from 1 to 4 carbon atoms, R 2 =hydrogen, chlorine, bromine, an alkyl radical with 1 to 12 carbon atoms, preferably with 1 to 4 carbon atoms; a hydroxyl, amino, acylamino such as C 1-4 -alkanoylamino, ureido, carbamoyl, phenyl, carboxyl or phosphono group, R 3 =hydrogen, chlorine, bromine, an alkyl radical with 1 to 12 carbon atoms, preferably with 1 to 4 carbon atoms, a phenyl radical or the groups mentioned for R 1 , but independently of R 1 , and R 2 and R 3 together may, with the carbon atom to which they are attached, form a 5- to 7-membered carbocyclic ring which may optionally be interrupted by nitrogen, or R 2 and R 3 together may represent an alkylene radical, preferably a methylene radical, or a C 1-4 , preferably C 1-2 , alkylene radical optionally substituted by phosphono groups and/or carboxyl groups; or together R 2 and R 3 may represent a double-bonded oxygen atom. Upon heating, the salt forms a foam which protects the substrate.

What is claimed is: 
     
       1. A substrate having coated on its surface a flameproofing composition comprising a filler and at least one zinc, calcium, strontium, magnesium, aluminum, chromium (III) or iron salt of phosphonopropionic acid or phosphonosuccinic acid. 
     
     
       2. A substrate according to claim 1, wherein the metal salt is an acid metal salt. 
     
     
       3. A substrate according to claim 1, wherein the salt is a zinc or magnesium salt. 
     
     
       4. A substrate according to claim 1, wherein the salt is primary zinc phosphonopropionate. 
     
     
       5. A substrate according to claim 1, wherein the salt is magnesium phosphonopropionate. 
     
     
       6. The process of flameproofing a substrate which comprises coating said substrate with a flameproofing composition comprising a filler and at least one zinc, calcium, strontium, magnesium, aluminum, chromium (III) or iron salt of phosphonopropionic acid or phosphonosuccinic acid.